Conversion of hydrocarbons and recovery of conversion products



March 27, 1956 D. J. QUIGG ET AL 2,739,877

CONVERSION OF HYDROCARBONS AND RECOVERY OF CONVERSION PRODUCTS Filed Aug. 21, 1950 2 Sheets-Sheet l f V I7 1 [I LJO '55 i-E as; (l U S H F E ED I c 0 4 O A e 1 #(Q: 35 -37 74 73 JXGEJ U O C35 76 r72. SEPARATION ZONE 75 1 WATER 7 69 J 24 1 6| CONDENSATION ZONE 5? -27 GASO| |NE\ 66 2 W 2 LIQUID 62 LIGHT GAS OIL; 57 PRODUCT CIVIL HEAVY GAS o|| SEPARATION STRIPPING CHAMBER" WATER E WATER O T INVENTORS.

D. J. QUIGG v. SCARTH 5.6. STEWART WWW ATTORNEYS March 27, 1956 D. J. QUIGG ET AL 2,739,877

CONVERSION OF HYDROCARBONS AND RECOVERY OF CONVERSION PRODUCTS Filed Aug. 21, 1950 2 Sheets-Sheet 2 INVENTORS. o. J. QUIGG v. SCARTH y 5.0. STEWART A 7 TO/PNE VS Unit States CONVERION F HYBROCA'RBQNS AND RECOVERY OF *CQNVERSKQN PRQDUCTS Application August 21, 195i), Serial No. 189,638

Claims. (Ci. 23-260) This invention relates to the conversion of hydrocarbons. In one of its more specific aspects it relates to process and apparatus for treating hydrocarbon oils. in another of its more specific aspects it relates to processing of heavy hydrocarbon oils to form vaporous and liquid cracking products and to the recovery of such products.

Various methods are taught in the art for cracking hydrocarbon oils. Many such hydrocarbon materials, when subjected to high cracking temperatures, decompose in a large proportion to form carbonaceous by-products or, if mild cracking conditions are employed to minimize such decomposition, low oil conversions are obtained. When cracking heavy oils at a high conversionin accordance with many known methods, extensive coke formation takes place, and the on-time cracking period is short lived, since the equipment must then be shut down and the carbonaceous by-product removed. Our invention is concerned with process and apparatus for effecting an improved conversion of hydrocarbon oils to produce liquid and vaporous cracking products, for operating such a process over prolonged periods of time, and for an efficient recovery of the products formed.

In a preferred embodiment of our invention we utilize pebble heater apparatus in conjunction with novel appatus for recovering total liquid and vaporous cracking products.

A pebble heater system, or pebble heater apparatus, as it is often called, usually comprises a series of substantially vertically-extending chambers, often in vertical alignment with each other. Usually two such chambers are employed and are connected by a relatively narrow interconnecting conduit, or throat. The top or upper chamber is commonly referred to as the pebble heating chamber, and the lower chamber as the fluid reaction or iluid heating chamber. A combustion zone, or chamber, is positioned adjacent or in close proximity to the sides of the lower portion of the heating chamber. Hot combustion gas from the combustion chamber is passed through the mass of pebbles in the pebble heating chamber. A hot gas source other than a combustion chamber, such as that obtained by burning a fuel on the surface of solid, flowing contactrnaterial, is sometimes employed. A contiguous mas of particulate contact material, often referred to as pebbles, fills the pebble heatirn chamber, the interconnecting throat, and the fluid reaction or heating chamber, and flows downwardly as a contiguous mass through these chambersby gravity. Pebbles are discharged from the bottom of the fluid reaction chamber at a controlled rate and returned, usually by elevating means, to the inlet in the upper-portion of the pebble heating chamber. A contiguous moving pebble mass thereby fills the pebble heating chamber, fluid heating chamber, and interconnecting throat, at all times. 7

The term pebble as used throughout the specificationdenotes any. solid refractory material-of-flowable form and size that can be utilized to carry heat from one zone to another. Pebbles are preferably substantially spherical and about ,5 inch to 1 inch in diameter, the preferred range being about /4 inch to A inch. Pebbles are formed of a refractory material which will Withstand temperatures at least as high as the highest temperature attained in the pebble heating chamber, and must be capable also of witsstandin-g temperature changes within the apparatus. Refractory materials such as metal alloys, ceramics, or other satisfactory material may be utilized to form such materials. Silicon carbide, alumina, periclase, thoria, beryllia, stellite, zirconia, and mullite may be satisfactorily used to form such pebbles or may be used in admixture with each other or with other materials. Pebbles formed of such materials, when properly fired, serve very well at high temperatures. Some pebbles withstand temperatures up to about 3500- F. Pebbles which are used may be either inert or. catalytic, as used in any selected process.

Pebbleheater apparatus is generally employed in the thermal treatment or conversion of reactant materials, often hydrocarbons. Operation of such a pebble system generally involves circulating a contiguous pebble mass through the pebble heating chamber, interconnecting throat and reaction chamber. That portion of the pebble mass descending through the heating chamber is heated to a suitable predetermined temperature above a desired treating or conversion temperature in heat exchange relation with combustion gas or other hot gases from any desired source. Pebbles are often heated in the heating chamber to temperatures as high as from 2000 to 3000 F., and in some cases higher, dependent upon the temperature requirements of the subsequent treating step. The heated pebbles passing through the reaction chamber are contacted directly with the material to be treated or converted for a suitable contacting time to efi'fect the desired treatment. The pebble mass, having given up heat to the material treated in the treating chamber, descends through the bottom of that chamber and is fed to an elevator for further handling, generally for transfer to an inlet at the top of the pebble heating chamber for reheating and recirculation through the system.

An object of our invention is to provide process and apparatus for converting hydrocarbons. Another object is to provide process and apparatus for the conversion of hydrocarbon oils to cracking product in improved yields. Another object is to provide a process for conver-ting heavy oils to produce liquid eflluent from the cracking zone in large volume, and for the recovery of light cracking products from the liquid efi luent as vapor. Another object is to provide for the utilization of pebble heater apparatus in cracking heavy hydrocarbon oils over prolonged operating periods. Another object is to provide for the separation of pebbles and oil discharged from a reaction chamber, of a pebble heater system, as a single efiluent stream, and for the recovery of cracking product from the oil thus separated. Other objects and advantages will be apparent to one skilled in the art from the accompanying discussion and disclosure.

In carrying out one embodiment of our invention, a contiguous mass of pebbles is gravitated through a pebble heating chamber, an oil conversion chamber, and a throat interconnecting these chambers; a contiguous mass of pebbles thereby filling these chambers and the interconnecting throat. The pebble mass in the heating chamber is heated to a temperature generally within the limits of about 1000 to 1700 F. This is done by any suitable means, preferably by the introduction of a combustible fuel' mixture into the heating chamber, burning same in the chamber, and passing the resulting hot combustion gases through the heating chamber in contact with the pebblemass. The pebble mass gravitated from the heating chamber enters the oil cracking chamber through the pebble throat with very little heat loss. A heavy hydrocarbon oil, often an oil residuum having a gravity within the limits of about 10 and 25 API, is introduced into the oil conversion chamber in concurrent fiow relation with the pebble mass therein.

Unvaporized oil is withdrawn together with pebbles as a single effluent stream from a lower portion of the cracking chamber. Oil is separated from the pebble-oil stream as it is passed through the pebble discharge conduit, and pebbles thus separated are recirculated through the system. Liquid oil thus separated is graviated to an oil stripping chamber maintained at a pressure lower-than that of the cracking chamber. Oil gravitated into the oil stripping chamber is partially vaporized and is passed downwardly through an upper portion of the stripping chamber and then immediately in an upward direction through an adjacent upper portion thereof, so as to separate liquids from vapors in the oil thus introduced, by centrifugal force. Liquid thus separated is collected in the bottom of the stripping chamber.

superheated vaporous product is withdrawn from an upper portion of the oil cracking chamber, and is passed through the liquid oil body in the stripping chamber, to maintain the oil in a heated condition, to strip products of cracking therefrom, and to remove such products as vapors. superheated vapors are passed through the liquid oil body, either without any added cooling, or after first being cooled to a minor extent, as for example 100 to 300 F., to minimize polymerization of olefins therein. Total vapors, i. e., vaporous cracking product passed through the liquid oil body and that stripped from the liquid body, are withdrawn from the stripping chamber and cooled while still in direct communication with the interior of the stripping chamber, to condense a high proportion of the vapors and to maintain the stripping chamber under the requisite reduced pressure. Efiluents are withdrawn from the cooling step, and cracking produc are recovered therefrom.

With reference to the attached drawings, specific embodiments of the process and apparatus of our invention, are diagrammatically illustratedv Figure 1 is a diagrammatic flow sheet illustrating one form of apparatus by means of which the process of our invention can be carried out. Figure 2 is a view taken along the line 22 in Figure 1 showing a preferred arrangement of baffle plate and oil inlet conduit together with the vapor outlet conduit, in the oil stripping chamber of Figure l. Figures 3 and 5 show specific arrangements of pebble feeder valves and stripping fluid conduits that can be utilized in regulating flow of pebbles from the pebble heater apparatus of Figure l and for effecting a separation of oil and pebbles when discharged together from the pebble heater system. Figure 4 illustrates a vibratory screen positioned in the pebble heater outlet conduit and its utilization in effecting separation of oil from pebbles, discharged togetherfrom the pebble heating system. it is to be understood that the drawings are diagrammatic only and that they can be altered in many respects by those skilled in the art and yet remain within the intended scope of the invention.

Referring to Figure l, pebble heating chamber is an upright elongated chamber lined with insulation means 11 for withstanding high temperatures required in heating pebbles in chamber 10, to temperatures as high as about 2000 F. and above in accordance with the process 'of our invention. Oil cracking chamber 12 is an elongated upright chamber similarly equipped with insulating means 11, and positioned below chamber 10 and connected therewith by insulated throat condit 14. Pebble inlet conduit 16 and gas effluent conduit 17 are provided in a top portion of chamber 10. Fuel and air inlet: conduits 18 and 19 respectively are connected with chamber 10 at a point in the lower portion thereof, through conduit 21. Oil feed inlet conduit 22 is provided in a central portion of chamber 12, and comprises a single inlet conduit or a plurality, as desired. Conduit, or conduits 22 are extended into chamber 12, if desired.

Pebble outlet conduit 23 in the bottom portion of chamber 12 extends laterally and downwardly therefrom and has a perforate section 24 as as least a portion of its bottom side. A liquid collector chamber 26 encompasses perforate section 24, and is afiixed at its upper end to conduit 23. Stripping chamber 27 is disposed below collector chamber 26 and contains a downwardly extending bafile plate 28, which divides an upper portion of chamber 27 into a first section 29 and a second section 31. Baflle plate 28 is sealed to the top of chamber 27, as illustrated in Figure 2, and causes sections 29 and 31 to communicate with each other only at their lower ends, i. e., at points below end 32 of bafile plate 28. Conduit 33, for transferring liquid oil from chamber 26 to chamber 27, extends from a lower portion of chamber 26 to an upper portion of chamber 27 in direct communication only with section 29 therein. Liquid level controller 34 is positioned in close proximity to liquid collector chamber 26 and in communication with the interior thereof. Valve 36 in conduit 33 is actuated in response to liquid level controller 34. Conduit 37 extends from an upper portion of chamber 12 to a lower portion of chamber 27 at a point below the end 32 of bafiie plate 28. Liquid level controller 38 is disposed in close proximity to chamber 27, and is in communication with the interior thereof at a point below end 32 of bafiie plate 28. An oil outlet conduit 39 is provided in the bottom portion of chamber 27. Valve 41 in conduit 39 is actuated in response to liquid level controller 38. Gas outlet conduit 42 is disposed in an upper portion of chamber 27 in direct communication only with section 31 therein.

With reference to Figure 3, pebble feeder device 43 is positioned in outlet conduit 23 at a point above, or slightly overlapping, the upstream end of perforate section 24. Feeder 43 can be any suitable device for regulating the fiow of pebbles and oil from chamber 12, preferably a feeder of the star valve type. Steam inlet conduit 49 is disposedat a'point in the upper portion of conduit 23, below or in close proximity to the downstream end of feeder 43.

With reference to Figure 4, a vibratory screen 44is positioned in conduit 23 above at least one opening in the bottom side of conduit 23 encompassed by liquid collector chamber 26. Screen 44 is hinged to a side wall of conduit 23, such as at point 46, and is caused to oscillate by any desired means, such as cam means 47 extending into conduit 23 and positioned subjacent a lower end portion of screen 44. In the embodiment shown, cam means-47 is a cam operated to turn continuously in one direction or reversibly as desired, to cause screen 44 to oscillate. Steam inlet conduit 49a is disposed at a point in an upper portion of conduit 23, above screen 44, preferably near the upstream end of screen 4-4. I

In Figure 5, pebble feeder means 43 is positioned in conduit 23 downstream from perforate section 24, and steam inlet conduit 49b is disposed at a point in conduit 23 above perforate section 24. By-pass conduit 48 extends from an upper portion of collector chamber 26 to conduit 43 at a point downstream from feeder 43.

Referring again to Figure 1, pebble mass 51 is heated in chamber 10 by introducing fuel, such as natural gas, with air from lines 18 and 19 respectively, through line 21 into a lower portion of chamber 10 and burning the fuel-air mixture therein. Hot combustion gases thus formed are passed upwardly through chamber 10 transferring heat to the cooler pebbles introduced thereinto through conduit 16. Relatively cool combustion gases are withdrawn from chamber 10 through conduit 17. We prefer to heat pebbles in chamber 10 to a temperature generally within the limits of from 1000 to 1700 F., and accordingly, adjust the proportions of air and fuel burned, as desired.

Pebbles heated in chamber 10 are gravitated through throat14 andehamber 12. Hydrocarbon oil feed, gen

erally an oil residuum having a gravity generally within the limits of from 10 to 25 AP}, is introduced'into chamber 12 in concurrent flow relation with pebble mass 51 therein, at a single point or at a plurality of'points. We prefer generally to introduce the oil feed into contact with pebble mass 51 in chamber 12 at one or more points in a central portion thereof, and to regulate the rate of flow of oil feed so as to quickly cool the pebbles initially contacted, to a temperature at which a large proportion of oil feed remains unvaporized. In this manner, the vaporized portion of the oil feed is passed upwardly through pebble mass 51 and cracked incontact with. hot pebbles to form cracking product in high'yield, while at the same time being superheated; and the unvaporized oil portion in chamber 12 is partially cracked while it is passeddownwardly in concurrent fiowrelation with cooler pebbles in pebble mass 51 in chamber 12. We prefer to introduce a sealing fluid chemically inert to the reaction materials in the process system, as for example steam, into throat 14 to prevent passage therethrough of heating gases from chamber 10 and of hydrocarbon vapors from chamber 12. Liquid oil is discharged from chamber 12, together with pebbles, as a single efiluent stream through pebble outlet conduit 23. The single pebbleoil stream in line 23 is passed over perforate-section 24, through which oil is separated from the oil-pebble stream and ispermitted to pass downwardly throughperforate section 24 into liquid collector chamber 26, while pebbles substantially free of oil pass from conduit 23 into elevating means 52, wherein they are elevated and then returned through conduit 53 to pebble inlet 16. Any oil. not separated while the pebble-oil stream is passed over-section 24- is collected in a lower part of the elevating system 52 and returned to stripping zone 27 through line 54. Any water. present in line 54 is removed through line 50, thelatter comprising condensate of any steam added to :thesystemas. a fluid seal or to facilitate oil-pebble sep aration in conduit 23, as described hereafter. It is necessary to maintain a liquid seal between liquid collector 26 and stripping chamber 27, for the reason that chamber 27 is operated at a pressure lower than that utilized in collector 26, which reduced pressure may be as low as from 10 to 50 mm. Hg, absolute, and as high as 600 mm. Hg, absolute, or higher, dependent on the specific oil-feed processed. This liquid seal is generally. maintained by means of liquid level controller 34 in communication with the oil liquid level 56 in chamber 26,.together with valve 36 actuated by controller 34 to permit the requisite flow of oil through conduit 33 to maintain level. 56. Oil

passed through valve 36, upon being subjected to reduced pressure, partially vaporizes, and is directed immediately downwardly through section 29 in chamber 27 across liquid oil body 57 maintained in a lower portion of chamber 27, as described hereafter, and then immediately in an upward direction through section 31 to outlet conduit 42. In this manner, a large proportion of the light cracking products in the liquid oil from collector 26. is separated as vapor, and remaining unvaporized oil is collected in the bottom of chamber 27. Liquid level controller 38 regulates the rate of liquid oil discharged from chamber 27 in response to liquid level 58.

Superheated vaporous cracking product is withdrawn from an upperportion of chamber 12 through conduit 37, and is passed into oil body 57 in chamber 27, preferably at a point in the lower portion thereof, and through oil body 57. In this manner, the oil body 57 is maintained in a heated condition under the reduced pressure conditions in chamber 27, and remaining valuable cracking productsare stripped therefrom, and removed in admixture with the vapors passed therethrough. Under these conditions substantially the last remaining portions of desirable cracking product are separated from the heavier residual materials, the latter beingwithdrawn from the system through conduit 39.

:Totalvaporous materials'in chamber 27' are withdrawn throughisection 31" via outlet'conduit- 42, and passed into condensationzone 61, wherein the va'pors are cooled .line through line 66, -a light'gas oil through line 67, a

heavy gas oil through line 68, and any water through line 60, the latter comprising condensate of'any steam added to the system as a fluidseal or to facilitate oil-pebble separation in conduit 23, as described hereafter. Uncondensed vapors are withdrawn from condensationzone 61 through line 69 and compressor 71, and passed into gaseous productseparation zone 72, comprising conventional separation equipment, such as fractionators,'condensors, storage tanks, and'the like, not individually illustrated, for recovering light hydrocarbons. Light cracking products are withdrawn from zone 72, as for example,

methane and hydrogen through line 73, Czs through line 74, Cas through line 76, and Cis through line 77, and any water through line 75, the latter comprising condensate of any steam added to the system as a fluid seal or to facilitate oil-pebble-separation in conduit 23, as described hereafter.

Asillustrated in Figure 3,.pebble feeder 43, positioned upstream from perforate section 24in conduit 23, provides for control of pebble flow to regulate the depthof the pebble layer. overiperforate section 24. In the opera- .tion of this embodiment, a fluid stripping medium, generally'steam, is introduced throughthe inlet conduit 49 .to facilitate removal of liquid oil materials from thepebble' surfaces.

As illustrated in Figure 4, vibratory screen 44 causes agitation of pebbles in conduit 23 so as to cause oil to be separated by its own inertia and to gravitate into liquid collecting zone 26. Stripping medium can be utilized when desired'by the introduction of ,same' into-contact with pebbles passingover 'vibratory' screen 44, through inletconduit 49a.

As illustrated in'Figure 5, pebble feeder 43 is positioneddownstream from perforate section 24 and pebbles and oil are maintained oversection 24'while at the same time being contacted with a stripping medium, generally steam, introduced through conduit 49b. By-pass conduit 48 provides for release of. stripping medium from liquid collector 26 into conduit 23 downstream from pebble feeder 43.

For convenience and clarity, certain apparatus such as pumps, surge tanks, accumulators, valves, and the. like, have notbeen shown inthe drawing. Obviously, such modifications of the present invention may be practiced without departing from the scope of the invention.

We prefer to employ oil feed inlet rates sufficiently high to cool pebbles initially contacted to a. temperature often as low as from 300 to 506 F. lower than that of the pebbles initially introduced into the oil conversion chamber. In this manner, the temperature conditions'are relatively mild to prevent undue carbon formation and to form desired gas oil and otherlighter liquid cracking product materials in high yield, while at the same time pebbles at a much higher temperature are contacted with feed vapors initially formed upon contacting pebbles in the conversion chamber, and these feed vapors are then further cracked at relatively higher temperatures .to produce desired light hydrocarbons in high yield,.and superheated. In'this embodiment, it is generally advantageous to introduce pebbles in a weight ratio to oil intothe oil conversionchamber as 'lowas' about 1131, and generally not'higher than'aboutBO: 1'. Onemanner in'which'the oil araasvv feed can be introduced into the pebble mass is to extend the oil inlet conduit, or conduits, into the pebble mass at a plurality of points in a downstream portion thereof, so

that the pebble mass is more uniformly contacted with oil feed, and hot pebbles initially introduced into the chamber are efiiciently utilized in cracking feed vapors, to provide for higher yields of light hydrocarbons from heavy oils than obtained heretofore.

Our invention is well applied to processes generally termed vis breaking, in which case a crude bottoms fraction generally containing from 5 to about 20 per cent bottoms is treated at a temperature generally within the limits of from about 1000 to 1400 F. at a very short contact time to convert fuel oil components therein to lighter gas oils. The lighter gas oils recovered from such a process have utility as catalytic cracking feed stock, thus providing for a more efiicient utilization of the crude fraction.

Our invention provides for the removal of undesirable polymeric materials formed in the vaporous efliuent withdrawn from chamber 12. These polymers are scrubbed from the vapor during the contact of vapors and oil in the oil stripping chamber. This feature of our invention provides a convenient means for removing these undesirable polymeric by-products from the effluents, being particularly advantageous in the preparation of feed stocks for catalytic conversion, as for example, isomerization and alkylation.

The temperature of the body of liquid oil in stripping chamber 27 is maintained at a level somewhat higher than the temperature of pebbles discharged from the oil conversion chamber, by transfer of heat from the hot vaporous cracking product contacted therewith, and is regulated by the reduction in pressure in the stripping chamber, which causes cooling to take place by virtue of vaporization of liquids therein. We prefer to utilize a temperature of liquid oil in the, stripping chamber to within a range of from about 450 to 600 F., although temperatures as high as 700 F. and in some cases higher, can be utilized. At these higher temperatures, particularly above 700 F., some further cracking of liquid oil in the stripping chamber may take place, and in many instances this is a desirable feature. However, the amount of cracking to be conducted in the stripping chamber, if any, is regulated by the amount of superheated gases passed through line 37 and by the reduction in pressure effected in the stripping chamber. Generally, we prefer to heat the oil at a temperature in the preferred range discussed above at an absolute pressure within the limits of about 100 to 400 mm. of mercury.

As will be evident to those skilled in the art, various modifications can be made or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

We claim:

1. Apparatus for converting hydrocarbon oils, comprising a pebble heating chamber; an oil conversion chamber positioned below said heating chamber; a pebble throat conduit extending from a lower portion of said heating chamber to an upper portion of said oil conversion chamber; pebble inlet means in an upper portion of said pebble heating chamber; means for heating pebbles in said pebble heating chamber; reactant material inlet means intermediate the ends of said oil conversion chamber; a pebble outlet conduit in the lower portion of said oil conversion chamber and extending laterally and downwardly from said oil conversion chamber, at least a portion of the bottom side of said pebble outlet conduit containing a perforate section; an elevator connected at one end to said pebble outlet conduit and at the other end to said pebble inlet conduit; a liquid collector chamber encompassing said perforate conduit section and aifixed at its upper end to said pebble outlet conduit; a stripping chamber disposed below said collector chamber; a partition extending downwardly from the top of said stripping chamber dividing an upper portion of said stripping chamber into a first section and a second section in communication with each other only at their lower ends; a conduit extending from a lower portion of said collector chamber to an upper portion of said stripping chamber in direct communication only with said first section; a conduit extending from an upper portion of said oil conversion chamber to a lower portion of said stripping chamber; an oil outlet conduit in a lower portion of said stripping chamber; a gas outlet conduit in an upper portion of said stripping chamber in direct communication only with said second section therein; and condensing means connected with said gas outlet conduit.

2. Apparatus for converting hydrocarbon oils, comprising an elongated upright pebble heating chamber; an elongated upright oil conversion chamber positioned below said pebble heating chamber; a pebble throat extending from a lower portion of said heating chamber to an upper portion of said oil conversion chamber; a gas inlet conduit in a lower portion of said heating chamber; a gas outlet conduit in an upper portion of said heating chamber; a pebble inlet conduit in an upper portion of said heating chamber; an oil inlet conduit in a central portion of said oil conversion chamber; a pebble outlet conduit in a lower portion of said oil conversion chamber and extending laterally and downwardly from said oil conversion chamber; said laterally extending conduit containing openings in its bottom side each a size to prevent passage of pebbles therethrough and to permit flow of oil therethrough; a liquid oil collector chamber encompassing said openings and affixed at its upper end to said laterally extending conduit; a first liquid level controller in communication with the interior of said collector chamber; an upright elongated stripping chamber disposed below said collector chamber; a substantially vertically dis posed partition extending downwardly from the top of said stripping chamber dividing an upper portion thereof into a first section and a second section in communication with each other only at their lower ends; a conduit extending from a lower portion of said collector chamber to an upper portion of said stripping chamber in direct communication only with said first section; a valve in the last said conduit operatively connected to said first liquid level controller; a conduit extending from an upper portion of said oil conversion chamber to a lower portion of said stripping chamber; a second liquid level controller in communication with the interior of said stripping chamber at a point below the end of said partition; an oil outlet conduit in a lower portion of said stripping chamber; a valve in said oil outlet conduit operatively connected to said second liquid level controller; a gas outlet in said stripping chamber in direct communication with said second section therein; and condensing means connected to said gas outlet conduit.

3. Apparatus comprising a cracking chamber; oil inlet means in said cracking chamber; means for heating said oil to a cracking temperature in said chamber; an oil outlet conduit in a lower portion of said chamber; a liquid oil collector chamber afiixed to said oil outlet conduit and adapted to receive liquid oil therefrom; an oil stripping chamber; a partition extending downwardly from the top of said stripping chamber dividing an upper portion thereof into a first section and a second section'in communication with each other only at their lower ends; a conduit extending from a lower portion of said collector chamber to an upper portion of said stripping chamber in direct communication only with said first section; a conduit extending from an upper portion of said cracking chamber to a lower portion of said stripping chamber; an oil outlet conduit in a lower portion of said stripping chamber; and a gas outlet conduit in an upper portion of said stripping chamber in direct communication with said second section therein.

4. Apparatus for converting hydrocarbon oils, comprising an oil 'conversionchamber; apebble inletconduit in-anupper portion of said oil conversion chamber; at least one 'oil' inlet conduit in said'oil conversioncharnber; means for heatingpebbles and for introducing pebbles thus' he'ated into said oil conversion chamber; a pebble o'utlet'conduit in a lower portion of saidconversion chamber and extending laterally and downwardly from said oil conversion chamber; the bottom side of said pebble outlet conduit containing a plurality of openings each of'a sizetoprevent passage of pebbles therethrough;a liquid collector chamber encompassing said plurality of openings 'a'nd'afiixed at its upper end to said conduit; an oil stripping chamber disposed below said liquid collector chamber; a partition extending downwardly from the top of said stripping chamber dividing an upper portion of said stripping chamber into a first section and a second section in communication with each other only at their lower ends; a conduit extending from a lower portion of said collector chamber to an upper portion of said stripping chamber in direct communication only With said first section; a conduit extending from an upper portionofsaid oil conversion chamber to a lower portion ofsaid stripping chamber; an oil outlet conduit in a lower portion of said stripping chamber; a gas outlet conduit in an upper portion of said stripping chamber in direct communication only with said second section therein; and pressure reducing means connected with said-stripping chamber.

5.-Apparatus for converting hydrocarbon oils, comprising'a pebble heating chamber; an oil conversion chamber positioned below said heating chamber; a pebble throat conduit extending from a lower portion of of said heating chamber to an upper portion of said oil conversion chamber; pebble inlet means in an upper portion of'said pebble heating chamber; means for-heating pebbles in said pebble heating chamber; oil inlet conduit means in an upper portion of said'oil conversion chamber; a pebble outlet conduit in the lower portion of said oil conversion chamber and extending laterally and downwardly from said oil conversion chamber; a perforate section in the bottom side of said pebble outlet conduit; a pebble feeder means in said pebble outlet conduit upstream from said perforate section; a stripping fiuid inlet conduit in a side of said pebble outlet conduit intermediate said feeder means and the downstream end of said perforate section; a liquid collector chamber encompassing said perforate section and aflixed at its upper 'end'to said pebble outlet conduit; a stripping chamber disposed below said collectorchamber; a partition-extending downwardly from the top-of said stripping chamber dividing an upper portion of said stripping chamber intoa first section and a second section in communication with each other only at their lower ends; a conduit extending from a lower portion of said collector chamber to an upper portion of said stripping chamber in direct communication only with said first section; -a conduit extending from an upper portion of said oil conversion chamber to a lower portion of said stripping chamber; an oil outlet conduit in a lower portion of said stripping chamber; a gas outlet conduit in an upper portion of said stripping chamber in direct communication only with said second section therein; and pressure reduction means connected with said gas outlet conduit.

6. A pebble heater device for converting hydrocarbon oils, comprising a pebble heating chamber; an oil conversion chamber positioned below said heating chamber; a pebble throat conduit extending from a lower portion of said heating chamber to an upper portion of said oil conversion chamber; pebble inlet means in an upper portion of said pebble heating chamber; means for heating pebbles in said pebble heating chamber; oil inlet conduit means for admitting oil feed into said oil conversion chamber; a pebble outlet conduit in a lower portion of said oil conversion chamber and extending laterally and downwardly from said oil conversion chamber; a perforat section in' "the bottom sideot'said pebble out-let conduit cornp'rising openings of'a size to-prevent pebble fi'owtherethtough; pebble feeder meansinsai'd conduit downstream *from said' perforate section; a stripping flui'd inlet conduit in said' pebble outlet conduit positioned above said perforate section; aliquid collector chamber encompassingsaid perforate section and ailixed'at its upper endto said pebble'outlet conduit; a bypassconduit ex tending from an upper portion of saidcollector chamber tosaid' conduit at a point downstream from said feeder means; a stripping chamber disposed'belowsaid collector chamber; a partition extending downwardly from the top of said stripping chamber dividing an upper'portion of said stripping chamber into a first section and a second section in'communication with each other only at their lower ends; a conduit extending from a lower p'ortion'of said collector chamber to an upper portion of said stripping chamberin direct communication'only with said first'-'s'ec= ti'on; a conduit extending from an upper portion 'of's'aid oil conversion chamber to a lower'portion of said stripping chamber; an oil outlet conduit in a lower portion of said'strippin'g chamber; a gasoutlet conduit in an upper portion of said stripping chamber in direct communication with said second section therein; and condensing means connected with said outlet conduit.

7. Apparatus for converting hydrocarbon oils, compris ing apebble heating chamber; an oil conversion cham ber positioned below said heating chamber; a pebble throat conduit extending from a lower portion of said heating chamber to an upper portion of said oil conversion chamber; pebble inlet meansin an upper portion of said pebble heating chamber; means for heating'pebblesinsaid'pebble heating chamber; oil feed inlet'meansin said oil conversion chamber; a pebble outlet conduit in the lower-portion of said oil conversion'chamberex tending laterally and downwardly therefrom; at least one opening in the'bottom side of said 'outletconduit; a vibratory screen positioned over said 'opening'and'affixed to a lowerside wall of said pebble outlet conduit 'at'a point upstream from said opening; means for causing said vibratory screen to oscillate; a liquid collector chamber encompassing such openings as above described in the bottom sideof said outlet conduit, and atfixed atits upper end tos'aid conduit; a stripping chamber disposed below said collector chamber; a partition extending downwardly frorn=the top of said strip-ping chamber dividing an upper portion'of said stripping chamber into a first section and a second'section in communication with each other only at theirlower ends; a conduitextending from a lower portion of said collector chamber to an upper portion of said stripping chamber in direct communication only with said first section; a conduit extending from an upper-portion of said oil conversion chamber to a:-lower portion of said-strippingchamber; an oiloutlet conduit in a-lower portion of said stripping chamber; and'a: gas outlet conduit in an upper portion of-said stripping chamber in direct communication with'saidsecond section therein.

8. A pebble heater device for converting hydrocarbon oils, comprising a pebble heating chamber; anoil conversion chamber positioned below said heating chamber; a pebble throat conduit extending from a lower portion of said heating chamber to an upper portion of said oil conversion chamber; pebble inlet means in an upper portion of said pebble heating chamber; means for heating pebbles in said pebble heating chamber; a pebble outlet conduit in a lower portion of said oi-l conversion chamber and extending laterally and downwardly from said oil conversion chamber, at least one opening in the bottom side of said outlet conduit and having a size limited to prevent passage of pebbles therethrough; a liquid collector chamber encompassing all such openings in said pebble outlet conduit described above and afiixed at its upper end to said conduit; a stripping chamber disposed below said collector chamber; a partition extending downwardly from thetop of said stripping chamber dividing an upper portion of said stripping chamber into a first section and a second section in communication with each other only at their lower ends; a conduit extending from a lower portion of said collector chamber to an upper portion of said stripping chamber in direct communication only with said first section; a conduit extending from an upper portion of said oil conversion chamber to a lower portion of said stripping chamber; an oil outlet conduit in a lower portion of said stripping chamber; and a gas outlet conduit in an upper portion of said stripping chamber in direct communication with said second section therein.

9. In a pebble heater apparatus comprising a pebble heating chamber positioned above and in open communication with a conversion chamber and pebble elevator means, the upper part of which is in open communication with said pebble heating chamber and the lower part of which is in open communication with said conversion chamber by means of a pebble conduit, the improvement which comprises an opening in the under part of said conduit, said opening being in open communication with a stripping chamber positioned below said opening, a vibratable perforate member positioned across said opening and having perforations of such size as to retain refractory pebbles, and cam means for vibrating said perforate member.

10. In a pebble heating apparatus comprising a pebble heating chamber, a reaction chamber positioned below said pebble heating chamber and in open communication therewith, and an elevator adapted to convey pebbles from said reaction chamber to said pebble heating chamber, said reaction chamber being in communication with said elevator through a pebble conduit, the improvement which comprises, in combination: liquid collection means positioned below said conduit and in open communication therewith through an opening in said conduit, a perforate member positioned across said opening and having perforations of such size as to retain pebbles, pebble feeding means within said conduit between said opening and said reaction chamber, and fluid introduction means adjacent said feeding means.

11. In a pebble heating apparatus comprising a pebble heating chamber, a reaction chamber positioned below said pebble heating chamber and in open communication therewith, and an elevator adapted to convey pebbles from said reaction chamber to said pebble heating chamber, said reaction chamber being in communication with said elevator through a pebble conduit, the improvement which comprises, in combination: liquid collection means positioned below said conduit and in open communication therewith through an opening in said conduit, a vibratable perforate member positioned across said opening and having perforations of such size as to retain pebbles, a rotatable cam for vibrating said perforate member, and fluid introduction means opposite said member.

12. In a pebble heating apparatus comprising a pebble heating chamber, a reaction chamber positioned below said pebble heating chamber and in open communication therewith, and an elevator adapted to convey pebbles from said reaction chamber to said pebble heating chamber, said reaction chamber being in communication with said elevator through a pebble conduit, the improvement which comprises, in combination: liquid collection means positioned below said conduit and in open communication therewith through an opening in said conduit, a perforate member positioned across said opening and having perforations of such size as to prevent fiow ofpebbles into said liquid collecting means from said conduit, means for introducing fluid into said conduit at a locus opposite said perforate member, pebble feeding means positioned within said conduit intermediate said perforate member and said elevator, and by-pass means adapted to maintain open communication between said fluid collection means and a locus in said conduit intermediate said pebble feeding means and said elevator.

13. Stripping apparatus comprising, in combination: a container vessel; a partition extending downwardly from the top of said vessel to a point intermediate the topand the bottom and laterally to the walls thereof, thus providing two substantially unobstructed sections intercommunieating only at their lower ends; inlet means at an upper part of one of said sections; outlet means at an upper part of the remaining section; inlet means at a lower part of said vessel below said partition; and drawofi means in the bottom of said vessel.

14. In a cracking system comprising a cracking chamber, an oil inlet in said cracking chamber, means for partially vaporizing oil introduced into said cracking chamber, and outlet means, at a lower part of said cracking chamber, for removing oil from said cracking chamber, the improvement which comprises in combination; a stripping chamber in communication with said outlet means; pressure reduction means for partially vaporizing oil in said stripping chamber; means for collecting and maintaining a body of unvaporized liquid in a lower part of said stripping chamber; and a conduit in open communication with an upper part of said cracking chamber and with a lower part of said stripping chamber.

15. An apparatus according to claim 14 wherein said means for collecting and maintaining a body of unvaporized liquid in said stripping chamber comprises a liquid drawofi pipe at the bottom of said stripping chamber, a valve positioned in said drawotf pipe, and a liquid-level controller adapted to actuate said valve and maintain a liquid level at a predetermined height in said stripping chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,990,878 Nelson Feb. 12, 1935 2,220,696 Watson Nov. 5, 1940 2,226,261 Rivkin Dec. 24, 1940 2,259,487 Payne Oct.21, 1941. 2,374,151 Wolk et a1 Apr. 17, 1945 2,487,795 Evans Nov. 15, 1949 2,532,613 Dutcher Dec. 5, 1950 2,571,342 Crowley, Jr. Oct. 16, 1951 FOREIGN PATENTS 165,133 Germany Nov. 10, 1905 

1. APPARATUS FOR CONVERTING HYDROCARBON OILS, COMPRISING A PEBBLE HEATING CHAMBER; AN OIL CONVERSION CHAMBER POSITIONED BELOW SAID HEATING CHAMBER; A PEBBLE THROAT CONDUIT EXTENDING FROM A LOWER PORTION OF SAID HEATING CHAMBER TO AN UPPER PORTION OF SAID OIL CONVERSION CHAMBER; PEBBLE INLET MEANS IN AN UPPER PORTION OF SAID PEBBLE HEATING CHAMBER; MEANS FOR HEATING PEBBLES IN SAID PEBBLE HEATING CHAMBER; REACTANT MATERIAL INLET MEANS INTERMEDIATE THE ENDS OF SAID OIL CONVERSION CHAMBER; A PEBBLE OUTLET CONDUIT IN THE LOWER PORTION OF SAID OIL CONVERISON CHAMBER AND EXTENDING LATERALLY AND DOWNWARDLY FROM SAID OIL CONVERSION CHAMBER, AT LEAST A PORTION OF THE BOTTOM SIDE OF SAID PEBBLE OUTLET CONDUIT AT ONE END TO PERFORATE SECTION; AN ELEVATOR CONNECTED AT ONE END TO SAID PEBBLE, OUTLET CONDUIT AND AT THE OTHER END TO SAID PEBBLE INLET CONDUIT; A LIQUID COLLECTOR CHAMBER ENCOMPASSING SAID PERFORATE CONDUIT SECTION AND AFFIXED AT ITS UPPER END TO SAID PEBBLE OUTLET CONDUIT; A STRIPPING CHAMBER DISPOSED BELOW SAID COLLECTOR CHAMBER; A PARTITION EXTENDING DOWNWARDLY FROM THE TOP OF SAID STRIPPING CHAMBER DIVIDING AN UPPER PORTION OF SAID STRIPPING CHAMBER INTO A FIRST SECTION AND A SECOND SECTION IN COMMUNICATION WITH EACH OTHER AT ONLY AT THEIR LOWER ENDS; A CONDUIT EXTENDING FROM A LOWER PORTION OF SAID COLLECTOR CHAMBER TO AN UPPER 